Mr Straw told activists in Blackburn on Thursday that voters would have to decide at the next election which party "best deserves" their "future trust".

"That in the end is the key choice at the next election."

'Dodgy dossier'

He acknowledged that the public had lost faith in Labour, but suggested it could persuade people to "reinvest their trust with us" if the party could overcome Tory attempts to spread cynicism in politics.

The Conservatives are keen to highlight the trust issue.

During his response to Gordon Brown's Budget statement on Tuesday, Michael Howard compared the chancellor's figures to the prime minister's claims about Iraq's weapons of mass destruction.

Issues of war and peace, life and death do have a very damaging effect on the credibility of politicians

Menzies CampbellLib Dem foreign affairs spokesman

The Lib Dems are also keen to highlight the trust issue, with Charles Kennedy has claiming voters had a "fundamental lack of trust in the prime minister".

And the Green Party unveiled a billboard opposite the Palace of Westminster accusing the government of lying over the Iraq war.

'Battle of words'

Former education secretary Estelle Morris told BBC News 24 that there was a "real problem of trust" between the public and the politicians.

She said she did not feel her own colleagues could be trusted, but suggested the "three-cornered relationship" between the press, politicians and the public had a hand in the issue.

The public was often turned off by sitting on the sidelines in "the battle of words" between the politician and the journalist, she added.